# prior mean

### Description

Internal function. Finds the sample mean of the n-vector **y** for use in specifying the prior mean *{\boldsymbolμ}_0*; see Section 2 of the referenced article for further details.

### Usage

1 | ```
priormeanobs(YI, tobs)
``` |

### Arguments

`YI` |
The N times (n-1) matrix with rows being the values of |

`tobs` |
Row vector of n observation times (in increasing order, same for each subject). |